Background: In 2011, 721,800 healthcare-associated infections (HAIs) were reported in the United States. The hospital environment has been increasingly recognized as an important determinant of HAI acquisition and prevention of HAIs has become a top priority for the U.S. Department of Health and Human Services (HHS). Terminal cleaning of a patient room is recognized as a critically important process to help prevent HAIs and involves extensive cleaning and disinfection of the room after a patient has been discharged from the room and before the subsequent patient has been admitted to the room. Pulsed xenon ultraviolet light (PX-UV) has been shown to be effective in killing a variety of pathogens including endospores of Clostridium difficile. PX-UV works quickly ? the entire cycle time for use in a hospital room is 15 minutes. To date, the clinical impact of adding PX-UV to terminal cleaning has not been demonstrated in clinical trials with sham controls or in a crossover design. The long-term goal of this project is to establish the efficacy of terminal cleaning plus PX-UV in reducing rates of HAIs due to the following multi-drug resistant oranisms (MDROs): C. difficile, vancomycin- resistant enterococci (VRE), Klebsiella pneumoniae and Escherichiae coli producing extended-spectrum beta- lactamases (ESBLs), methicillin-resistant Staphylococcus aureus (MRSA) and Acinetobacter baumannii. The objective of this application is to conduct a prospective, sham controlled, double-blinded, interventional crossover trial to compare standard terminal cleaning plus PX-UV (intervention) with standard terminal cleaning plus sham PX-UV (control) with crossover at 12 months, following a 6-month washout period. Outcome measures include the rates of HAIs, as well as the recurrence of genetically identical clinical strains of HAIs among patients on study units. The study will be conducted in 2 hospitals covering 16 total hospital units at Detroit Medical Center. Our central hypothesis is that the addition of PX-UV to standard terminal cleaning will be associated with a significant reduction in the rate of HAIs, as well as a reduction in the recovery of genetically identical strains of MDROs. The impact of PX-UV disinfection on rates of HAIs on study units will be determined by comparing rates of HAIs on a) study units where PX-UV is added to standard terminal cleaning practices to b) units where a sham UV disinfection system is added to standard terminal cleaning; and by comparing rates of HAIs on the same medical ward during each of two 12-month phases of a crossover study (one phase when a PX-UV device is added and one when a sham device is added to standard terminal cleaning). At the conclusion of the proposed project, novel data will be generated from this rigorously controlled study regarding the effectiveness of PX-UV in reducing HAIs in a representative, real-world healthcare setting.